Electrolytic capacitor and method for producing same

Abstract

Disclosed is an electrolytic capacitor including a capacitor element. The capacitor element includes an anode body having a dielectric layer formed at a surface of the anode body, and an electrolyte layer disposed adjacent to the dielectric layer. The electrolyte layer contains a conductive polymer doped with a dopant, conductive particles, and a non-aqueous solvent.

The invention claimed is: 
     
       1. An electrolytic capacitor, comprising a capacitor element, wherein
 the capacitor element includes an anode body having a dielectric layer formed at a surface of the anode body, and an electrolyte layer disposed adjacent to the dielectric layer, 
 the electrolyte layer contains a conductive polymer doped with a dopant, conductive particles, and a non-aqueous solvent, 
 the anode body has a porous portion at the surface, 
 an average particle diameter of the conductive particles is larger than an average pore diameter of the porous portion, 
 the conductive polymer is in a particle form, and 
 an average particle diameter of the conductive polymer is smaller than the average pore diameter of the porous portion. 
 
     
     
       2. The electrolytic capacitor according to  claim 1 , wherein
 the dopant is a polymer dopant containing an acidic group, and 
 the electrolyte layer contains an electrolyte solution including the non-aqueous solvent and a base component dissolved in the non-aqueous solvent. 
 
     
     
       3. The electrolytic capacitor according to  claim 2 , wherein a content of the base component in the electrolyte solution is 0.1 mass % or more and 20 mass % or less. 
     
     
       4. The electrolytic capacitor according to  claim 1 , wherein a total mass of the conductive polymer and the dopant contained in the electrolyte layer is larger than a mass of the conductive particles contained in the electrolyte layer. 
     
     
       5. The electrolytic capacitor according to  claim 1 , wherein the conductive particles are particles of a conductive carbon material. 
     
     
       6. The electrolytic capacitor according to  claim 1 , wherein the conductive particles include at least one kind of particles selected from the group consisting of carbon black particles, carbon nanotube particles, graphite particles, and graphene particles. 
     
     
       7. The electrolytic capacitor according to  claim 1 , wherein
 the electrolyte layer includes a polymer layer constituted of the conductive polymer, 
 the polymer layer includes a first polymer layer formed on the dielectric layer, and a second polymer layer formed on the first polymer layer, and 
 a content (mass %) of the conductive particles in the second polymer layer is larger than a content (mass %) of the conductive particles in the first polymer layer. 
 
     
     
       8. The electrolytic capacitor according to  claim 1 , wherein
 the dopant is polystyrene sulfonic acid, and 
 the conductive polymer is poly(3,4-ethylenedioxythiophene). 
 
     
     
       9. A method for producing an electrolytic capacitor, the method comprising:
 a step (i) of preparing a capacitor element precursor including an anode body having a dielectric layer formed at a surface of the anode body, 
 a step (ii) of forming a polymer layer containing a conductive polymer doped with a dopant, and conductive particles, so as to be adjacent to the dielectric layer, by an impregnation treatment, and 
 a step (iii) of impregnating the polymer layer with a non-aqueous solvent, wherein 
 the anode body has a porous portion at the surface, 
 an average particle diameter of the conductive particles is larger than an average pore diameter of the porous portion, 
 the conductive polymer is in a particle form, and 
 an average particle diameter of the conductive polymer is smaller than the average pore diameter of the porous portion. 
 
     
     
       10. The method according to  claim 9 , wherein
 the dopant is a polymer dopant containing an acidic group, and 
 the step (iii) is a step of impregnating the polymer layer with an electrolyte solution including the non-aqueous solvent and a base component dissolved in the non-aqueous solvent. 
 
     
     
       11. The method according to  claim 9 , wherein the impregnation treatment in the step (ii) is an impregnation treatment (x) of impregnating the capacitor element precursor with a dispersion including the conductive polymer doped with the dopant and the conductive particles. 
     
     
       12. The method according to  claim 9 , wherein
 the impregnation treatment in the step (ii) includes:
 an impregnation treatment (y) of impregnating the capacitor element precursor with a first dispersion including the conductive polymer doped with the dopant, and 
 an impregnation treatment (z) of impregnating the capacitor element precursor with a second dispersion including the conductive particles. 
 
 
     
     
       13. The method according to  claim 9 , wherein
 the dopant is polystyrene sulfonic acid, and 
 the conductive polymer is poly(3,4-ethylenedioxythiophene). 
 
     
     
       14. An electrolytic capacitor, comprising a capacitor element, wherein
 the capacitor element includes an anode body having a dielectric layer formed at a surface of the anode body, and an electrolyte layer disposed adjacent to the dielectric layer, 
 the electrolyte layer contains a conductive polymer doped with a dopant, conductive particles, and a non-aqueous solvent, 
 the electrolyte layer includes a polymer layer constituted of the conductive polymer, 
 the polymer layer includes a first polymer layer formed on the dielectric layer, and a second polymer layer formed on the first polymer layer, 
 both the first polymer layer and the second polymer layer contain the conductive particles, and 
 a content (mass %) of the conductive particles in the second polymer layer is larger than a content (mass %) of the conductive particles in the first polymer layer.